The human knee is subjected to a wide variety of compressive, bending, twisting and lateral forces, particularly when engaging in sports, and appliances such as knee braces or cages supporting the knee are widely used. Knee braces in their simplest form, comprise a sleeve of elastic fabric which receives the knee region, permits bending, but provides external mechanical support and bracing.
Knee cages often include stays or stiffening means, leg encircling straps are commonly used, and in order to provide lateral strength and support hinges are often incorporated into the cage.
Difficulty is encountered when using hinges with knee braces or cages in that the natural hinge interconnection between the femur and tibia does not produce pivoting about a fixed axis, but rather, a rolling interconnection occurs across the knee cartilage and a fixed pivot axis is not present. Accordingly, hinge devices used with knee braces and cages must accommodate the natural hinging action if the cage is not to interfere with normal knee use, and various types of hinges are employed with knee cages.
In prior art knee cages and braces using a flexible cover the hinge means are usually incorporated into the knee cover, such as by sewing, wherein the relationship of the hinge means to the cover is fixed. Such a fixed hinge does not permit accommodations of variations in knee structure and requires that the cage be accurately located upon the knee in order to achieve maximum comfort. The location of the cage cover on the knee to permit optimum hinge operation may not coincide with the desired locating of the cover with respect to the user's knee, and in such instances discomfort will result due to the necessity for the cover to be slightly displaced from the optimum position, or the hinge means will not be ideally located.
It is an object of the invention to provide a knee cage of the wrap around type which may be readily placed upon the knee, and wherein hinge means are associated with the cage cover, and are adjustably positionable thereon in order to assure the optimum locating of the hinge with respect to the cage cover.
Another object of the invention is to provide a knee cage of a wrap around type which may be quickly placed upon the wearer's knee and provides excellent lateral support by means of a multicentric metal hinge.
A further object of the invention is to provide a wrap around knee cage utilizing metal hinge means which may be readily removed from, and attached to, the outer cover of the cage at a variety of locations to permit custom positioning of the hinge relative to the knee being supported.
Yet a further object of the invention is to provide a multicentric hinge for knee braces and cages wherein multicentric pivoting between rigid hinge elements is achieved, yet the hinge elements are maintained in parallel planar relationship and supported against relative lateral displacement.
In the practice of the invention a cover of trapezoidal configuration includes a soft foam inner surface, and an outer surface of fabric having loop means defined thereon. At the central region of the cover an opening is formed which is located behind the knee to augment the cover flexibility during knee bending.
Four elastic straps are sewn to the cover at their inner ends, and the outer ends include hooks for cooperating with the cover outer surface loop means whereby the cover, and its straps, may be quickly wrapped about the knee.
The cage cover includes lateral portions disposed at the sides of the knee, and hinge means are located at such lateral portions. The hinge means each consist of a pair of elongated rigid metal elements interconnected by a multicentric pivot arrangement, and the hinge elements are each received within a pocket having hook means defined on the inner surface thereof, and loop means defined on the exterior surface. Thus, upon the hinge element pockets gripping the loop means of the cover lateral portions the cage hinges can be located upon the lateral portions as desired in such a manner to provide excellent lateral support of the knee and the adjustable locating, and multicentric pivoting, minimizes interference of knee movement by the hinge.
The multicentric hinge of the invention includes metal elements each having a flat inner end, and one of the elements includes a bearing plate located in spaced parallel relationship to the inner end wherein the other element inner end is disposed intermediate the bearing plate and associated inner end. Pins supporting the bearing plate are received within an irregularly shaped cavity in the other element inner end, and this cavity includes a recess portion which defines a fulcrum when receiving a pin therein. The dimensions and spacing of the pins in relationship to the cavity configuration is such that the pins and cavity permit multicentric pivoting between the hinge elements between desired angular limits, and the hinge will support the knee against excessive angular pivoting, as well as provide lateral support.